Web/API/MessageChannel

From Get docs

The MessageChannel interface of the Channel Messaging API allows us to create a new message channel and send data through it via its two MessagePort properties.

Note: This feature is available in Web Workers.

Properties

MessageChannel.port1 Read only
Returns port1 of the channel.
MessageChannel.port2 Read only
Returns port2 of the channel.

Constructor

MessageChannel()
Returns a new MessageChannel object with two new MessagePort objects.

Example

In the following example, you can see a new channel being created using the MessageChannel.MessageChannel constructor.

When the IFrame has loaded, we register an onmessage handler for  MessageChannel.port1 and transfer MessageChannel.port2 to the IFrame using the window.postMessage method along with a message.

When a message is received back from the IFrame, the onMessage function simply outputs the message to a paragraph.

var channel = new MessageChannel();
var output = document.querySelector('.output');
var iframe = document.querySelector('iframe');

// Wait for the iframe to load
iframe.addEventListener("load", onLoad);

function onLoad() {
  // Listen for messages on port1
  channel.port1.onmessage = onMessage;

  // Transfer port2 to the iframe
  iframe.contentWindow.postMessage('Hello from the main page!', '*', [channel.port2]);
}


// Handle messages received on port1
function onMessage(e) {
  output.innerHTML = e.data;
}

For a full working example, see our channel messaging basic demo on Github ([[../../../../../../mdn.github.io/dom-examples/channel-messaging-basic/index|run it live too]]).

Specifications

Specification Status Comment
HTML Living StandardThe definition of 'Message channels' in that specification. Living Standard  

Browser compatibility

Update compatibility data on GitHub

Desktop Mobile
Chrome Edge Firefox Internet Explorer Opera Safari Android webview Chrome for Android Firefox for Android Opera for Android Safari on iOS Samsung Internet
MessageChannel Chrome

Full support 4

Edge

Full support 12

Firefox

Full support 41

IE

Full support 10

Opera

Full support 10.6

Safari

Full support 5

WebView Android

Full support 4.4

Chrome Android

Full support 18

Firefox Android

Full support 41

Opera Android

Full support 11

Safari iOS

Full support 5.1

Samsung Internet Android

Full support 1.0

MessageChannel() constructor Chrome

Full support 4

Edge

Full support 12

Firefox

Full support 41

IE

Full support 10

Opera

Full support 10.6

Safari

Full support 5

WebView Android

Full support 4.4

Chrome Android

Full support 18

Firefox Android

Full support 41

Opera Android

Full support 11

Safari iOS

Full support 5.1

Samsung Internet Android

Full support 1.0

port1 Chrome

Full support 4

Edge

Full support 12

Firefox

Full support 41

IE

Full support 10

Opera

Full support 10.6

Safari

Full support 5

WebView Android

Full support 4.4

Chrome Android

Full support 18

Firefox Android

Full support 41

Opera Android

Full support 11

Safari iOS

Full support 5.1

Samsung Internet Android

Full support 1.0

port2 Chrome

Full support 4

Edge

Full support 12

Firefox

Full support 41

IE

Full support 10

Opera

Full support 10.6

Safari

Full support 5

WebView Android

Full support 4.4

Chrome Android

Full support 18

Firefox Android

Full support 41

Opera Android

Full support 11

Safari iOS

Full support 5.1

Samsung Internet Android

Full support 1.0

Legend

Full support  
Full support


See also